What is the difference between Polymer and MnO2 Tantalum?


Manganese dioxide (MnO2) and Conductive Polymer are two types of cathode materials used in Tantalum capacitors.

Electrolytic Capacitor Construction

The basic capacitor construction consists of two dielectric plates separated by a dielectric. In the case of electrolytic capacitors, one plate consists of a positively charged anode while the other consists a negatively charged anode. The anode of a tantalum capacitor is a porous pellet of sintered Ta metal. This porosity creates a large surface area within the pellet structure, which results in the tantalum capacitor’s high capacitance characteristic. The dielectric is tantalum pentoxide (Ta2O5). The cathode is a semiconductor material, either MnO2 or a conductive polymer.

About Polymer

Conductive organic polymeric materials were discovered by Alan Heeger, Alan MacDiarmid and Hideki Shirakawa. They were awarded the 2000 Nobel Prize in Chemistry for the discovery and development of conductive polymers. One of the first industrial applications of new polymer organic material was to replace manganese dioxide (MnO2) in tantalum capacitors.

Polymer Advantages

When used as the cathode material, polymer offers electrolytic capacitors several advantages.

  • ESR is available in the 1, 10, and 100 mOhm range
  • Turn-on reliability is significantly higher compared to MnO2
  • In the event of failure, polymers fail benign — they do not ignite.

KEMET Polymer Electrolytic capacitors can be identified in their datasheet where the name KO-CAP® is shown.

For more information see this article on Polymer Electrolytic Capacitors.

Added on:

Tuesday, March 15th, 2016